The proposed research would complement and extend a recently funded evaluation of a preventive intervention that targets aggressive/noncompliant behavior in first grade. Entitled "Low Cost Prevention of Conduct Disorders" (DA 12202), the currently funded study experimentally evaluates a low-cost, comprehensive intervention consisting of a one-year teacher-led children's social problem solving skills program (Webster-Stratton & Hammond, 1997) and training for teachers in classroom behavior management (Webster Stratton & Reid, 1999). In addition, a 12-week parent training program is provided to parents of children showing early behavior problems. Funding for that project covers the full costs of assessing intervention effects on teachers and 162 children who are already exhibiting problem behaviors. The proposed project has three aims: (1) To experimentally evaluate the efficacy of the two universal components of this intervention (social skills curriculum and teacher training) on a representative sample of first-grade children; (2) To estimate the full costs of the intervention, including the implicit costs for participants and their families; and (3) To perform a full economic evaluation of the universal and indicated components of the intervention. That evaluation will have two components. The first is a benefit-cost analysis capturing any averted costs generated by the intervention, including special education, mental health services, medical services, and social services. To capture the benefits of the intervention more fully, we also propose a cost-effectiveness analysis of key child and family outcomes, including a measure of health-related quality of life. Analyses of this measure represent cost-utility analysis, the first time this method has been applied in research on substance-abuse prevention. To fully address these aims, this proposal requests additional funding to accomplish the following tasks: (1) To provide a basis for evaluating the universal intervention, expand data collection to include 648 children (n=12 in each of the 54 study classrooms) who were not identified as high risk at baseline; (2) To improve the accuracy of key data for the benefit-cost study, supplement parental reports of service use with reviews of agency and provider records (for both the at-risk and universal samples); (3) To better support the long-term analyses of intervention impact and economic effectiveness, add two years of follow-up data collection for at-risk children in the currently funded study (grades 3 and 4 - two- and three-year follow-up); (4) Calculate the full costs of the intervention, including implicit costs (e.g. the time costs of parental participation); (5) Obtain supplemental data necessary to convert data on service use into expenditures or costs (e.g., special education budgets from school districts); (6) Conduct detailed economic analyses, including the calculation of net benefits and cost-effectiveness ratios and the analyses of the variation in net benefits across sub-groups of participants.